How to use this guide. Levels and risks vary by location and utility. Always check your utility’s Consumer Confidence Report (CCR) and the Tennessee Water Authority city guide for your area before choosing a filtration system. The filter effectiveness data below reflects general peer-reviewed performance — real-world results depend on certification level, flow rate, and maintenance. For contaminants of serious concern, always choose NSF/ANSI certified systems tested for that specific contaminant.

Which contaminants are most common in Middle Tennessee water?

All 17 city guides in the Tennessee Water Authority series show the same top contaminants above EWG’s conservative health guidelines. Understanding which ones are in your specific utility’s water tells you exactly which filters matter most for your home.

Disinfection Byproducts (TTHMs / HAAs)
All 17 city guides — 100% of Middle Tennessee surface water utilities show TTHMs and HAAs above EWG guidelines
Fix: Whole-house activated carbon
Bromodichloromethane
Detected above EWG in most TN utilities. Highest: Nolensville (8.12 ppb, 135x EWG) · Franklin (6.01 ppb, 100x EWG)
Fix: Activated carbon or RO
Chromium-6 (hexavalent)
Above EWG in most Middle Tennessee utilities — naturally occurring in Cumberland River, Stones River, and Harpeth River limestone geology
Fix: RO or ion exchange only
PFOA / PFOS (PFAS)
Above EWG in Milcrofton UD, Spring Hill WD, Brentwood-area utilities. Nashville MWS: Non-Detect (2024 CCR)
Fix: RO or GAC with PFAS media
Nitrate
Agricultural runoff into Harpeth, Duck, and Cumberland Rivers. Highest: NCGUD Smyrna source 1.77 ppm (12.6x EWG)
Fix: RO or ion exchange only
Hard Water (Ca/Mg)
Limestone geology across all counties. Ranges from 5.67 GPG (Clarksville) to 12+ GPG (Smyrna / Murfreesboro)
Fix: Water softener (ion exchange)
EWG Tap Water Database — Official Video
What’s Really in Your Drinking Water?
The Environmental Working Group’s Tap Water Database covers nearly 50,000 U.S. water utilities — including all 17 Middle Tennessee utilities in this guide. This video explains how the database works, what it reveals about legal-but-concerning contaminants, and why EWG’s health guidelines are more conservative than EPA limits.
Source: Environmental Working Group · ewg.org/tapwater
After watching: use the contaminant guide below to look up exactly what EWG found in your Middle Tennessee utility.

Contaminant Guide: What It Is, Where It Comes From, What Removes It

Search for a contaminant or filter by category. Click any card to expand the full source, health effects, and filtration detail.

Source
Form when chlorine or other disinfectants react with naturally occurring organic matter in source water. Includes chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Higher in surface water utilities (rivers and lakes) than groundwater.
Health effects
Linked to increased cancer risk (bladder, colorectal), potential reproductive issues including low birth weight and birth defects, and other effects with chronic exposure above EWG’s conservative guidelines. EPA limit: 80 ppb (annual average). EWG guideline: 0.15 ppb.
Removed by:Activated Carbon (GAC)Carbon BlockCatalytic CarbonReverse Osmosis
★ In Middle Tennessee: All 17 city guides show TTHMs above EWG. Highest: Nolensville NCGUD 77.53 ppb LRAA (2024 CCR) — near EPA 80 ppb limit.
Source
HAA5 = five haloacetic acids (monochloroacetic, dichloroacetic, trichloroacetic, bromoacetic, dibromoacetic). HAA9 adds four more brominated forms. Form when disinfectants react with organic matter in source water — produced alongside TTHMs during chlorination.
Health effects
Associated with increased cancer risk (especially bladder), reproductive and developmental issues, and potential liver and kidney effects. Evidence of genotoxicity, particularly for HAA9. EPA limit: 60 ppb (HAA5). EWG guideline: 0.1 ppb.
Removed by:Activated Carbon (GAC)Carbon BlockCatalytic CarbonReverse Osmosis
★ In Middle Tennessee: All surface water utilities show HAAs above EWG. Smyrna WS 2025 CCR: HAA5 27.73 ppb. Nolensville NCGUD 2024 CCR: HAA5 36.55 ppb.
Source
Both are TTHM components. Bromodichloromethane forms when chlorine reacts with bromide-containing organic matter. Chloroform (trichloromethane) is typically the most abundant TTHM. Levels are higher in utilities using surface water from rivers with higher organic matter content.
Health effects
Bromodichloromethane: linked to cancer risk (liver, kidney, intestines), liver and kidney damage, reproductive issues (miscarriages, low birth weight), and immune effects. Chloroform: increases cancer risk; may cause pregnancy complications. Both within EPA limits at Middle Tennessee utility levels.
Removed by:Activated Carbon (GAC)Carbon BlockCatalytic CarbonReverse Osmosis
★ In Middle Tennessee: Franklin WD 6.01 ppb (100x EWG) · Nolensville NCGUD 8.12 ppb (135x EWG) · Smyrna WS 6.49 ppb (108x EWG). All above TN state avg (3.91 ppb) and national avg (5.89 ppb).
Source
HAA components formed during chlorination. Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are two of the five acids in the HAA5 group. More prevalent in surface water utilities. Levels rise with higher organic matter in source water.
Health effects
Potential cancer risk, liver effects, and developmental and reproductive toxicity shown in animal studies. Dichloroacetic acid: liver and kidney effects, potential for reproductive harm. Trichloroacetic acid: liver effects, potential cancer risk at high exposures.
Removed by:Activated Carbon (GAC)Carbon BlockCatalytic CarbonReverse Osmosis
Source
Per- and polyfluoroalkyl substances used in consumer products (non-stick cookware, stain-resistant coatings, firefighting foam). Enter water through industrial discharges, landfill leachate, and agricultural application of PFAS-contaminated biosolids. Extremely persistent — do not break down in the environment or human body. EPA finalized 4 ppt MCL for PFOA/PFOS in April 2024; utilities have until 2029 to comply.
Health effects
Cancer, endocrine disruption, accelerated puberty, liver and immune system damage, thyroid changes, and reproductive effects. PFBS, PFHpA, PFHxA are “short-chain” replacements for PFOA/PFOS with similar but potentially less severe profiles. All accumulate in the body. No safe level has been established. EWG guideline: 0.09 ppt.
Removed by:GAC with PFAS mediaReverse Osmosis (best)Ion Exchange (partial)
★ In Middle Tennessee: PFOA above EWG in Milcrofton UD, Spring Hill WD, Brentwood-area utilities. Nashville MWS: Non-Detect (2024 CCR). EPA 4 ppt MCL effective 2024; utilities have until 2029.
Source
Fertilizer chemical — contaminates drinking water through agricultural and urban runoff and discharges from municipal wastewater treatment plants and septic tanks. Enters Middle Tennessee rivers (Harpeth, Duck, Cumberland) from surrounding farmland. Higher in areas with more agricultural activity.
Health effects
For infants under 6 months: oxygen deprivation (blue-baby syndrome, methemoglobinemia) — can be life-threatening. Increased cancer risk with long-term exposure. No acute risk for healthy adults at typical Middle Tennessee levels. EPA limit: 10 ppm. EWG guideline: 0.14 ppm. Never boil water to remove nitrate — boiling concentrates it.
Removed by:Reverse OsmosisIon Exchange (anion)Activated carbon: NOBoiling: concentrates it
★ In Middle Tennessee: All surface water utilities above EWG. Highest via NCGUD 2024 CCR: Smyrna source 1.77 ppm (12.6x EWG).
Source
Widely used agricultural herbicide. Enters drinking water primarily through runoff from treated farmland. Most prevalent in corn-growing regions with surface water sources. Persists in soil and water. EPA limit: 3 ppb.
Health effects
Endocrine disruptor linked to reproductive and developmental effects (low birth weight, birth defects, altered hormone levels) and possible increased cancer risk (non-Hodgkin lymphoma). Associated with cardiovascular effects at high exposures. EWG guideline: 0.1 ppb.
Removed by:Activated Carbon (GAC)Reverse Osmosis
★ Unique finding: Springfield Water System (Red River source) confirmed atrazine at 0.260 ppb — 2.6x EWG guideline. Unusual in Middle Tennessee.
Source
From industrial discharges (chrome plating, dyes, pigments), corrosion inhibitors, and natural erosion of chromium-bearing geological deposits. In Middle Tennessee, primarily naturally occurring from limestone and rock formations in the Cumberland, Stones, and Harpeth River watersheds. No federal MCL specifically for hexavalent chromium (only total chromium at 100 ppb).
Health effects
Known human carcinogen (lung, stomach, intestinal cancers via ingestion). Skin irritation, respiratory issues, liver and kidney damage, and reproductive toxicity. EWG guideline: 0.02 ppb. Standard activated carbon filters are NOT effective for chromium-6.
Removed by:Reverse Osmosis (best)Specialized Ion ExchangeKDF media (converts to Cr-3)Activated carbon: NOT effective
★ In Middle Tennessee: Above EWG in nearly all surface water utilities. Naturally occurring in limestone geology across all 17 guide cities. Murfreesboro MWRD: 0.169 ppb (8.5x EWG guideline of 0.02 ppb). Look up your utility on EWG’s chromium-6 map →
Source
Primarily from corrosion of old lead service lines, lead solder, and brass/bronze fixtures in pre-1986 homes when water is acidic or low in minerals. Lead is NOT typically present in treatment plant output — it leaches from home plumbing. The utility’s Lead Service Line Inventory and lead action level tests reflect distribution system and home plumbing results combined.
Health effects
No safe level of exposure. In children: lowered IQ, learning and behavioral difficulties, slowed growth, and nervous system damage. In adults: high blood pressure, reproductive problems, nerve disorders, and memory issues. EPA MCLG = zero. Action level: 15 ppb. NSF/ANSI 53 certified filters are required for lead removal.
Removed by:NSF/ANSI 53 Certified CarbonReverse OsmosisIon Exchange
★ In Middle Tennessee: La Vergne, Smyrna WS, CUD Rutherford, and Gladeville UD all confirmed no lead in distribution system (LSLI complete). Nashville MWS: 0.8 ppb 90th% (0/85 exceeded AL, 2025 CCR).
Source
Naturally occurring in groundwater from geological deposits. Also from industrial discharges, mining, and agricultural runoff. More prevalent in groundwater than surface water. EPA limit: 10 ppb. EWG guideline: 0.004 ppb.
Health effects
Highly toxic inorganic arsenic. Long-term exposure causes skin lesions, cardiovascular disease, diabetes, and significantly increases risk of cancers (skin, lung, bladder, liver). Can impair neurological development in children. One of the most significant drinking water contaminants globally.
Removed by:Reverse Osmosis (best)Activated AluminaIron-Based MediaAnion Exchange
Source
Occurs naturally or from industrial discharges, drilling wastes, and metal refineries. Can leach from geological formations into groundwater. EPA limit: 2 ppm.
Health effects
High levels can increase blood pressure and cause cardiovascular, gastrointestinal, and neurological effects. Not a carcinogen at typical drinking water levels.
Removed by:Reverse OsmosisIon Exchange (water softener)
Source
Naturally occurring in rocks and soil. Can enter water from deposits or industrial sources. Essential in small amounts but excess can be harmful, especially for infants and children.
Health effects
Excess linked to neurological effects, impacts on memory, attention, and motor skills, and potential learning and behavioral issues in children. EPA health-based limit: 0.3 mg/L (secondary, for aesthetic reasons). Health advisory: 0.1 mg/L (infants).
Removed by:Oxidation + FiltrationManganese Dioxide Media (Greensand)Reverse Osmosis (point-of-use)
Source
Naturally occurring radioactive elements from uranium and thorium decay in rocks and soil. Higher in deep bedrock aquifers. More common in groundwater than surface water. Oil and gas extraction can sometimes elevate levels. EPA limit: 5 pCi/L combined.
Health effects
Radium emits alpha particles and increases lifetime cancer risk (especially bone cancer). May contribute to kidney issues with prolonged exposure. One of the more serious naturally occurring radioactive contaminants in drinking water.
Removed by:Reverse OsmosisIon ExchangeLime Softening
★ Unique finding in Middle Tennessee: Hendersonville Utility District (TN0000249) confirmed radium-226 and radium-228 above EWG guidelines — rare among this guide series. Old Hickory Lake (Cumberland River) formation.
Source
Occurs naturally in groundwater from rocks and soil. Intentionally added to many public water supplies for dental health at around 0.7 mg/L. Nashville MWS 2025 CCR: 0.68 ppm (by Metro source), 0.492 ppm (by Smyrna source). EPA limit: 4 mg/L.
Health effects
At 0.7 mg/L: dental health benefits. Above 2 mg/L: dental fluorosis (enamel discoloration in children). Above 4 mg/L: skeletal fluorosis. Recent reviews have examined potential links to neurodevelopmental effects at higher exposures. Most Middle Tennessee utilities are well within the 4 mg/L limit.
Removed by:Reverse OsmosisActivated AluminaBone Char Carbon
Source
Dissolved calcium and magnesium from limestone and dolomite rock. Middle Tennessee sits on limestone geology — all rivers and aquifers pick up mineral content as water flows through. Hardness is measured in grains per gallon (GPG) or mg/L. Treatment does not remove hardness unless a softener is installed.
Health effects & impacts
No direct health risk. Causes scale buildup in water heaters (reducing efficiency 8% per GPG per U.S. Dept. of Energy), appliance failure, pipe narrowing, soap scum, dry skin and hair, cloudy glassware, and stiff laundry. Tankless water heaters are especially vulnerable. Range in Middle Tennessee: 5.67 GPG (Clarksville) to 12+ GPG (Smyrna, Murfreesboro).
Removed by:Ion Exchange (water softener) — most effective whole-houseReverse Osmosis (point-of-use)Carbon filters: NOT effective
★ Middle Tennessee hardness ranges: Nashville 5.88 GPG (moderate) · Franklin 7.9 GPG verified (2025 CCR) · Smyrna/Murfreesboro 10–14 GPG (extremely hard).
Source
Intentionally added to public water systems as disinfectants to kill harmful bacteria, viruses, and other pathogens. Residual chlorine stays in the water through distribution to prevent recontamination. Nashville MWS 2025 CCR: avg 1.60 ppm chlorine (highest avg, 2025 CCR). Smyrna WS: 1.53 ppm highest RAA (2025 CCR). Maximum allowed: 4 mg/L.
Health effects
Chlorine itself at typical levels is not a health concern and is essential for public health. The concern is that residual chlorine in distribution pipes reacts with organic matter to form TTHMs and HAAs (disinfection byproducts). Directly toxic to aquarium fish at any level. Chloramines are harder to remove than free chlorine and require catalytic carbon.
Removed by:Activated Carbon (GAC) — free chlorineCatalytic Carbon — chloraminesVitamin C (shower filter)
Source
Naturally occurring or from industrial sources. Common in limestone and dolomite geological formations. No current EPA MCL, though EPA has a lifetime health advisory of 1,500 ppb for infants and 4,000 ppb for others.
Health effects
Can interfere with bone mineralization, especially in calcium-deficient diets. High levels potentially affect skeletal development. More of a concern for infants and children.
Removed by:Reverse OsmosisIon Exchange
Source
Naturally occurring or from industrial activities (fossil fuel combustion, mining, chemical manufacturing). No current EPA MCL for vanadium in drinking water.
Health effects
Potential for respiratory, gastrointestinal, and neurological effects at elevated exposures. Research on drinking water risks is ongoing. Not considered a primary concern at typical Tennessee utility levels.
Removed by:Reverse OsmosisSpecialized Ion Exchange
Source
Hydrogen sulfide produced by sulfur-reducing bacteria in groundwater or from natural mineral deposits. More common in well water than municipal surface water. Sulfates from natural mineral deposits. No primary EPA standard for hydrogen sulfide; sulfate has a secondary limit of 250 mg/L.
Health effects & impacts
Strong “rotten egg” odor and taste at low concentrations. Black or yellow staining on fixtures. Corrodes plumbing. Not typically a health risk at household levels but can irritate eyes, nose, and throat at high airborne concentrations. Sulfates may cause a laxative effect in infants at very high levels.
Removed by:Aeration + Catalytic CarbonManganese Dioxide MediaRO (sulfates)
No contaminants found matching your search. Try a broader term or clear the search.

Filter Effectiveness Matrix

Which filter removes which contaminant? This matrix covers 12 filter technologies across the most common contaminants detected above EWG guidelines in Middle Tennessee water. Use the search to find your specific contaminant.

✅ Effective
Partial Partial or conditional
❌ Not effective
Contaminant Category Activated Carbon (GAC) Carbon Block Catalytic Carbon Reverse Osmosis Ion Exchange KDF Media 0.5 Micron Filter Water Softener (salt-based) Distillation UV Sterilization

Important: Filter effectiveness varies significantly by certification level, contact time, flow rate, and maintenance. For contaminants of serious concern (lead, PFAS, nitrate), always choose NSF/ANSI certified systems tested for that specific contaminant. NSF/ANSI 42 = aesthetic (chlorine, taste, odor). NSF/ANSI 53 = health effects (lead, VOCs). NSF/ANSI 58 = reverse osmosis systems. A filter that is “capable” of removing a contaminant is not the same as one that is certified to do so.

Filter Technology Guide

Understanding what each filter technology actually does — and what it doesn’t.

Activated Carbon (GAC)
Removes: TTHMs, HAAs, chloroform, bromodichloromethane, PFAS (with PFAS media), atrazine, 2,4-D, chlorine, many organic chemicals, taste and odor compounds.
Does NOT remove: nitrate, chromium-6, heavy metals (except with special media), fluoride, dissolved salts, hardness, bacteria.
Reverse Osmosis (RO)
Removes: TTHMs, HAAs, PFAS, nitrate, chromium-6, lead, arsenic, barium, fluoride, radium, strontium, most dissolved solids, nanoplastics.
Does NOT remove: hydrogen sulfide, chlorine/chloramines (pre-filter required to protect membrane), dissolved gases.
Ion Exchange (IX)
Removes: Hardness (Ca/Mg) — water softeners. Nitrate, chromium-6, barium, radium — with specialized anion/cation resins. Lead, strontium.
Does NOT remove: chlorine, TTHMs, HAAs, organic contaminants, PFAS (standard softeners). Note: PFAS ion exchange requires specialized media.
Catalytic Carbon
Removes: Same as GAC, plus more effective against chloramines (standard GAC struggles with chloramines). TTHMs, HAAs, hydrogen sulfide, and other organics.
Does NOT remove: Same limitations as GAC — no nitrate, chromium-6, heavy metals, or dissolved inorganic salts.
KDF (Kinetic Degradation Fluxion)
Removes: Chlorine, heavy metals (lead, mercury, cadmium), hydrogen sulfide, scale. Converts hexavalent chromium (Cr-6) to trivalent chromium (Cr-3). Inhibits bacteria and algae growth in carbon filters.
Does NOT remove: Nitrate, PFAS, TTHMs (on its own), most organic chemicals. Usually used in combination with carbon.
UV Sterilization
Removes: Bacteria, viruses, and other biological contaminants. Effective against chlorine-resistant organisms like Cryptosporidium and Giardia.
Does NOT remove: Any chemical contaminants — TTHMs, HAAs, PFAS, nitrate, chromium-6, lead, hardness. UV only addresses biological concerns, not chemical ones.

What to Buy for Middle Tennessee Water

Based on the contaminant profiles across all 17 city guides, here is what most Middle Tennessee homeowners need:

1.
Whole-house activated carbon backwashing filter
Targets TTHMs, HAAs, bromodichloromethane, and chlorine at every tap and shower. Most important for surface water utility customers (Nashville, Franklin, Murfreesboro, Smyrna, Nolensville, etc.). Cost: $1,400–$4,500 installed.
2.
Under-sink reverse osmosis (drinking & cooking)
Removes what carbon can’t: chromium-6, nitrate, PFAS, fluoride, and all remaining contaminants. NSF/ANSI 58 certified. Produces water at 4¢/gallon. Most important for PFAS-concern areas (Milcrofton UD, Spring Hill WD) and infant formula preparation. Cost: $600–$2,000 installed.
3.
Water softener (ion exchange) — priority varies by city
Essential for Smyrna (12 GPG), Murfreesboro (12 GPG), La Vergne (11 GPG). Strongly recommended for Franklin (7.9 GPG), Spring Hill (9 GPG), Nolensville (8 GPG). Less urgent for Nashville (5.88 GPG) and Clarksville (5.67 GPG). Cost: $2,500–$4,500 installed.
4.
NSF/ANSI 53 certified point-of-use filter (lead — older homes)
For pre-1986 homes with potential lead solder at pipe joints. The utility distribution system may be lead-free (as confirmed in La Vergne, Smyrna, CUD Rutherford), but home plumbing can still leach lead. NSF/ANSI 53 certified only. Cost: $50–$300 under-sink unit.

Get your city’s specific contaminant profile.

Each of 17 Middle Tennessee cities has its own guide with verified CCR data.

Filter recommendations → Find a local pro
City water guides
Nashville → Franklin → Murfreesboro → Brentwood → Nolensville → Smyrna → La Vergne → Spring Hill → Hendersonville → Gallatin → Thompson’s Station → Bottled vs. Filtered Water →